JP2014091074A - Carbon dioxide recovery apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce introduction cost of a compressor and furthermore to reduce a space occupied for installation of the compressor.SOLUTION: A carbon dioxide recovery apparatus includes: an absorption part in which carbon dioxide-containing gas is brought into contact with absorption liquid; a regeneration part 140 releasing carbon dioxide from the absorption liquid containing carbon dioxide; a compressor 400 compressing recovered gas containing carbon dioxide discharged from the regeneration part; and heat exchangers 320a, 320b, 320c recovering heat generated accompanying the compression of the gas by the compressor. The compressor includes: a plurality of compression chambers 410, 412, 414 in which the recovered gas is compressed by rotation of the impellers 420, 422, 424; and a speed change mechanism transmitting rotating power different in number of revolutions to a plurality of shafts respectively. The compressor is of a centrifugal type in which the recovered gas serially flows between the plurality of compression chambers to enhance compressibility of the recovered gas. The heat exchangers are arranged on rear side of the plurality of the compression chambers respectively.

Description

  The present invention relates to a carbon dioxide recovery device that separates and recovers carbon dioxide from a mixed gas containing carbon dioxide such as exhaust gas accompanying combustion.

In plants such as thermal power plants, steelworks, and boilers, a large amount of fossil fuel (for example, coal, heavy oil, super heavy oil) is burned. Therefore, exhaust gas containing carbon dioxide (CO ₂ ), sulfur oxide (SOx), and nitrogen oxide (NOx) is discharged from the plant as the fossil fuel burns. Among the substances contained in exhaust gas, carbon dioxide is a cause of global warming, and its emissions into the atmosphere are regulated by the United Nations Framework Convention on Climate Change.

  Therefore, a technology (CCS) that separates and recovers carbon dioxide from exhaust gas containing carbon dioxide such as exhaust gas accompanying combustion and exhaust gas accompanying processes, and then exhausts the exhaust gas from which carbon dioxide has been removed to the atmosphere (CCS). : Carbon dioxide Capture and Storage) has been developed. A carbon dioxide recovery device using CCS makes an absorption liquid (an absorption liquid that does not absorb carbon dioxide, hereinafter referred to as a lean absorption liquid) contact with exhaust gas to absorb carbon dioxide contained in the exhaust gas lean. An absorption tower that removes carbon dioxide from exhaust gas by absorbing the liquid, and a regeneration tower that releases carbon dioxide from an absorption liquid that absorbs carbon dioxide (hereinafter referred to as a rich absorption liquid) and regenerates it into a lean absorption liquid The lean absorbent regenerated in the regeneration tower is reused in the absorption tower. The carbon dioxide released from the regeneration tower is compressed by the compressor and is not discharged into the atmosphere, but is stored in an underground aquifer or underground oil field, or dissolved in the ocean or river. To do.

  In the regeneration tower, in order to release carbon dioxide from the rich absorbent, it is necessary to heat the rich absorbent. Therefore, in order to reduce the operating cost of the carbon dioxide recovery device as a whole, reduction of energy required for the heating is desired.

  Therefore, a plurality of compressors are provided in series on the downstream side of the regeneration tower, and the heat generated when the recovered gas containing carbon dioxide and water vapor discharged from the regeneration tower is compressed by the compressor is recovered for each compressor. A technique for utilizing the recovered heat in the regeneration tower is disclosed (for example, Patent Document 1).

JP 2012-538 A

  In the technique of Patent Document 1 described above, a specific configuration of the compressor is not considered. For example, a configuration in which a plurality of separate compressors are installed can be assumed, but it is too expensive to introduce a plurality of compressors, and the space occupied for installation becomes excessive.

  Therefore, as a compressor, only one so-called single-shaft multi-stage compressor provided with a plurality of impellers on one shaft is arranged, and heat recovery is performed while compressing the recovered gas step by step for each impeller. Is also possible. However, in a single-shaft multi-stage compressor, it is difficult to adjust the rotation speed for each impeller. Therefore, if the recovered gas is compressed with a desired compression ratio with a small number of impellers, the shape of the impeller and the flow path Such a design becomes complicated. In addition, in order to compress the recovered gas at a desired compression rate, it may be necessary to arrange a large number of impellers. In such a case, as in the case where a plurality of separate compressors are installed, the introduction cost is reduced. In some cases, the space occupied for installation becomes excessive.

  Therefore, in view of such problems, the present invention is capable of reducing the space occupied for installing the compressor while reducing the introduction cost of the compressor without complicating the design work. It aims to provide a recovery device.

  In order to solve the above-mentioned problem, the carbon dioxide recovery device of the present invention is configured to bring a gas containing carbon dioxide into contact with an absorption liquid, absorb the carbon dioxide in the absorption liquid, and generate a carbon dioxide-containing absorption liquid. A carbon dioxide-containing absorbent, heating the carbon dioxide-containing absorbent, and releasing the carbon dioxide from the carbon dioxide-containing absorbent, thereby regenerating the carbon dioxide-containing absorbent into the absorbent, and discharging the carbon dioxide-containing absorbent. A passage line through which the recovered gas containing carbon dioxide and water vapor passes, a compressor provided in the passage line for compressing the recovery gas, and heat generated in association with compression of the recovery gas in the compressor A heat exchanging unit that collects and supplies the heat to the regeneration unit, and the compressor includes a plurality of shafts, a plurality of impellers fixed to one end of the shafts, and the plurality of shafts. And a plurality of compression chambers in which the recovered gas is compressed by rotation of the impeller, and a transmission mechanism that transmits rotational power having different rotational speeds to each of the plurality of shafts. The recovered gas is circulated through the plurality of compression chambers in order to increase the compression rate of the recovered gas, and the heat exchange section is provided at a subsequent stage of each of the plurality of compression chambers. It is arranged in.

  The carbon dioxide recovery device is provided in the passage line, and separates water from the recovered gas by recovering heat by the heat exchange unit, and water is separated by the gas-liquid separation unit. A recovery line through which the recovered gas passes, and the compressor is connected to the plurality of compression containers forming the outer walls of the plurality of compression chambers and the plurality of compression containers, and the transmission mechanism is A transmission container to be accommodated, each of the plurality of compression containers and the transmission container are coupled, the compression container and a plurality of connecting portions into which the shaft accommodated in the transmission container is inserted, and the shaft A pair of dry gas seals that are inserted and disposed opposite to each other in the axial direction of the shaft inside the connecting portion and prevent leakage of the recovered gas from the compression container to the transmission container. , The recovery line, and the connecting portion may be in communication with the enclosed spaces between the pair of the dry gas seal.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the space occupied for installation of a compressor, reducing the introduction cost of a compressor, without complicating design work.

It is a figure for demonstrating the structure of a carbon dioxide collection apparatus. It is a figure for demonstrating the structure of a compressor. It is explanatory drawing for demonstrating the connection part of a compression container and a compression container and a speed change container. It is explanatory drawing for demonstrating an example of the design calculation of a compressor.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(CO2 recovery device 100)
FIG. 1 is a diagram for explaining a configuration of a carbon dioxide recovery device 100 according to the present embodiment. As shown in FIG. 1, the carbon dioxide recovery device 100 includes a carbon dioxide separation and recovery unit 110 and a carbon dioxide compression unit 200.

  The carbon dioxide separation / recovery unit 110 separates carbon dioxide from the gas G containing carbon dioxide, and the carbon dioxide compression unit 200 compresses the carbon dioxide separated in the carbon dioxide separation / recovery unit 110. Hereinafter, specific configurations of the carbon dioxide separation and recovery unit 110 and the carbon dioxide compression unit 200 will be described.

(Carbon dioxide separation and recovery unit 110)
The absorption part (absorption tower) 120 is composed of, for example, a counter-current gas-liquid contact device, and brings a gas G containing carbon dioxide into contact with an absorption liquid (hereinafter, referred to as a lean absorption liquid L) to obtain a lean absorption liquid L absorbs carbon dioxide to produce a carbon dioxide-containing absorbent (hereinafter referred to as rich absorbent R).

  Here, the gas G is, for example, an exhaust gas accompanying combustion or an exhaust gas accompanying a process. The gas G is a temperature suitable for efficiently absorbing the carbon dioxide into the lean absorbent L in the absorption unit 120 (for example, 40 ° C). In addition, when the exhaust gas accompanying combustion and a process is high temperature, you may introduce | transduce into the absorption part 120, after cooling with a separate cooling device. The lean absorbent L is composed of an aqueous solution containing, as an absorbent, a compound having affinity for carbon dioxide such as alkanolamines, for example.

  Moreover, the absorption part 120 is provided with the filler 122 for enlarging the contact area of the lean absorption liquid L and the gas G in the inside. The filler 122 is made of an iron-based metal material such as stainless steel or carbon steel.

  In this embodiment, the gas G is introduced from the lower part of the absorption part 120, and the lean absorbent L is introduced from the upper part of the absorption part 120. Then, the gas G passes from the lower part to the upper part of the absorber 120 and the lean absorbent L passes from the upper part to the lower part of the absorber 120, that is, while the gas G and the lean absorbent L pass through the filler 122. The carbon dioxide in the gas G is absorbed by the lean absorbent L by contacting the gas and liquid. The gas C from which carbon dioxide has been removed is discharged from the top of the absorber 120. The lean absorbing liquid L generates heat by absorbing carbon dioxide, and the liquid temperature of the rich absorbing liquid R rises, so that the cooling condensing part 124 for removing water vapor or the like that can be contained in the gas C is absorbed by the absorbing part. You may provide in the upper part of 120.

  The delivery line 130 is a line (pipe) that connects the lower part of the absorption unit 120 and the upper part of the regeneration unit 140 described later.

  The preheating unit 132 collects heat (sensible heat) of the lean absorbent L flowing through a return line 160 described later, and heats the rich absorbent R flowing through the feed line 130.

  In addition, the rich absorbent R heated by the preheating unit 132 is further heated by the first heat exchange unit 310 described later in the delivery line 130. The heat treatment by the first heat exchange unit 310 will be described in detail later.

  The regeneration unit (regeneration tower) 140 is constituted by, for example, a countercurrent gas-liquid contact device, heats the rich absorbent R sent from the absorber 120 through the delivery line 130, and generates carbon dioxide from the rich absorbent R. By releasing, the rich absorbent R is regenerated to the lean absorbent L. Specifically, the reproduction unit 140 includes a main body 142 and a reboiler 150. The main body 142 is provided with a filler 144 made of an iron-based metal material such as stainless steel or carbon steel, for example, in the same manner as the absorbing portion 120.

  The reboiler 150 includes a circulation line 152 and a heating unit 154, and refluxes the rich absorbent R in the main body 142. Specifically, the circulation line 152 circulates the rich absorbent R by re-introducing the rich absorbent R from the bottom of the main body 142 and then reintroducing it into the main body 142. The heating unit 154 is composed of a steam heater, an electric heater, or the like, and heats the rich absorbent R flowing through the circulation line 152. In the circulation line 152, the rich absorbent R is also heated by a second heat exchange unit 320 described later. The heat treatment performed by the second heat exchange unit 320 will be described in detail later.

  The return line 160 is a line (pipe) that connects the bottom of the main body 142 and the top of the absorber 120.

(Flow of absorption liquid)
Subsequently, the flow of the absorbing liquid in the carbon dioxide separation and recovery unit 110 will be described. The rich absorbent R generated in the absorption unit 120 and stored at the bottom of the absorption unit 120 is sent to the top of the main body 142 of the regeneration unit 140 through the delivery line 130 by the pump 170a. The rich absorbent R is heated by the preheating unit 132 and the first heat exchange unit 310 while passing through the delivery line 130.

  The rich absorbent R introduced into the regeneration unit 140 passes through the filler 144 in the main body 142, is stored at the bottom of the main body 142, and is heated by the reboiler 150. Then, carbon dioxide is released from the rich absorbent R at the bottom of the main body 142 by heating by the reboiler 150.

  The lean absorbent L regenerated by releasing carbon dioxide in the regeneration unit 140 is returned to the upper part of the absorption unit 120 through the return line 160 by the pump 170b. Thus, the absorbing liquid circulates between the absorbing unit 120 and the regenerating unit 140. The lean absorbent L is cooled by the preheating unit 132 and the cooling unit 162 to a temperature suitable for carbon dioxide absorption in the absorption unit 120 while passing through the return line 160.

  On the other hand, the carbon dioxide released from the rich absorbent R in the regeneration unit 140 is discharged to the carbon dioxide compression unit 200 together with the water vapor.

(CO2 compression unit 200)
The passage line 210 is a line (pipe) through which the recovered gas X (carbon dioxide and water vapor) discharged from the regeneration unit 140 constituting the carbon dioxide separation and recovery unit 110 passes. Here, the temperature of the recovered gas X discharged from the regeneration unit 140 is, for example, 110 ° C., and the ratio of carbon dioxide: water vapor is 1: 1.

  The first compression unit 220 is provided in the passage line 210 and compresses the recovered gas X discharged from the regeneration unit 140 to, for example, 500 kPa (A). Note that Pa (A) indicates an absolute pressure with the absolute vacuum set to zero. The second compression unit 222 is provided in the passage line 210 and further compresses the recovered gas X compressed by the first compression unit 220 (for example, 900 kPa (A)). The third compression unit 224 is provided in the passage line 210 and compresses the recovered gas X compressed by the second compression unit 222 to, for example, 1300 kPa (A).

  The second heat exchanging unit 320 includes the recovered gas X from the first compression unit 220 on the downstream side of the first compression unit 220, the downstream side of the second compression unit 222, and the downstream side of the third compression unit 224. Heat (sensible heat) generated with compression of the gas, heat generated with compression of the recovered gas X by the second compression unit 222 (latent heat), and compression of the recovered gas X by the third compression unit 224 The accompanying heat (sensible heat) is recovered to heat the rich absorbent R flowing through the circulation line 152 that constitutes the carbon dioxide separation and recovery unit 110 described above.

  For example, the recovered gas X (for example, 200 ° C.) on the downstream side of the first compression unit 220 is cooled to 140 ° C. by the second heat exchange unit 320. The recovered gas X (for example, 200 ° C.) on the downstream side of the second compression unit 222 is cooled to 130 ° C. by the second heat exchange unit 320. The recovered gas X (for example, 170 ° C.) on the downstream side of the third compression unit 224 is cooled to 130 ° C. by the second heat exchange unit 320. Along with this, the 120 ° C. rich absorbent R flowing through the circulation line 152 is heated to 130 ° C. by the second heat exchange unit 320.

  Here, the recovered gas X is compressed by the second compression unit 222, and when heat is recovered by the second heat exchange unit 320, the water vapor in the recovered gas X is condensed into water. Therefore, the first gas-liquid separation unit 230 is provided on the downstream side of the second compression unit 222, on the downstream side of the second heat exchange unit 320, and on the upstream side of the third compression unit 224.

  The first gas-liquid separation unit 230 is provided on the downstream side of the second compression unit 222, and heat (latent heat) is recovered by the second heat exchange unit 320, so that water condensed in the recovered gas X ( Condensed water) is separated from the recovered gas X.

  The first heat exchanging unit 310 collects the heat (sensible heat) of the recovered gas X cooled by the second heat exchanging unit 320 on the downstream side of the third compressing unit 224, and sends the above-described delivery line 130. The rich absorbing liquid R that circulates is heated.

  For example, the recovered gas X (for example, 130 ° C.) cooled by the second heat exchange unit 320 is cooled to 120 ° C. by the first heat exchange unit 310. Accordingly, the 110 ° C. rich absorbent R flowing through the delivery line 130 is heated to 120 ° C. by the first heat exchanging section 310.

  The second gas-liquid separation unit 250 is provided on the downstream side of the third compression unit 224, and heat (sensible heat) is recovered by the first heat exchange unit 310 and further cooled by the cooling unit 252. The water condensed in the recovered gas X (condensed water) is separated from the recovered gas X.

  The recovery line 254 is a line (pipe) that connects the second gas-liquid separation unit 250 to, for example, a storage tank (not shown), and the recovery from which condensed water is separated by the second gas-liquid separation unit 250. Gas X is guided to a storage tank or the like. The component of the recovered gas X stored in a storage tank or the like is almost carbon dioxide, and is stored, for example, in an underground aquifer or underground oil field, or dissolved in the ocean or river. The collection line 254 communicates with a compressor 400 described later. The compressor 400 will be described in detail later.

  The first condensed water introduction line 260 is downstream of the bottom of the first gas-liquid separation unit 230 and the third compression unit 224 in the passage line 210, and performs heat recovery by the second heat exchange unit 320. This is a line (pipe) that connects a place to be performed and a place to perform heat recovery by the first heat exchange unit 310. The first condensed water introduction line 260 is provided with a pump 260a, and the condensed water separated in the first gas-liquid separation unit 230 is passed through the first condensed water introduction line 260 by the pump 260a. In the passage line 210, the heat is recovered by the second heat exchange unit 320 and the heat recovery by the first heat exchange unit 310 is introduced.

  The 2nd condensed water introduction line 270 is a line (pipe) which connects between the bottom part of the 2nd gas-liquid separation part 250, and the pump 170b and the cooling part 162 in the return line 160 mentioned above. The second condensed water introduction line 270 is provided with a cooling unit 272 and a pressure adjustment valve 274. The condensed water separated in the second gas-liquid separation unit 250 is cooled by the cooling unit 272, and the pressure is reduced. The pressure is adjusted by the regulating valve 274 and introduced between the pump 170 b and the cooling unit 162 in the return line 160 described above through the second condensed water introduction line 270.

  In the present embodiment, the first compression unit 220, the second compression unit 222, and the third compression unit 224 are configured by a compression chamber of a centrifugal compressor that compresses a fluid by a centrifugal force generated by rotation of an impeller. The Hereinafter, a specific configuration of the compressor will be described in detail.

  FIG. 2 is an explanatory diagram for explaining the configuration of the compressor 400, and schematically shows the structure of the compressor 400. As shown in FIG. 2, the compressor 400 includes a plurality of (here, three) compression units 220, 222, and 224 that compress the recovered gas X, and the recovered gas X is supplied to the compression units 220, 222, and 224. By increasing the flow rate, the recovery gas compression rate is increased.

  Specifically, the compressor 400 includes a compression chamber 410 constituting the first compression unit 220, a compression chamber 412 constituting the second compression unit 222, and a compression chamber 414 constituting the third compression unit 224. And. In the compression chamber 410, the inflow hole 410a into which the recovered gas X flows is connected to the pipe 410b (passage line 210) communicating with the main body 142 of the regeneration unit 140 described above, and the outflow hole 410c from which the recovered gas X flows out. The pipe 410d communicates with the heat exchanger 320a constituting the second heat exchange section 320 described above.

  The compression chamber 412 has an inflow hole 412a into which the recovered gas X flows in and communicates with the heat exchanger 320a through the pipe 412b, and an outflow hole 412c through which the recovered gas X flows out through the pipe 412d. , And communicated with the heat exchanger 320b constituting the second heat exchanging section 320 described above. The heat exchanger 320b communicates with the first gas-liquid separation unit 230 via the pipe 418a.

  In addition, the compression chamber 414 has an inflow hole 414a into which the recovered gas X flows in and communicates with the first gas-liquid separation unit 230 via the pipe 414b, and an outflow hole 414c through which the recovered gas X flows out It communicates with the heat exchanger 320c constituting the second heat exchanging section 320 described above via 414d.

  Therefore, the recovered gas X discharged from the regeneration unit 140 flows into the compression chamber 410. The recovered gas X compressed in the compression chamber 410 is recovered by the heat exchanger 320a and then flows into the compression chamber 412.

  The recovered gas X compressed in the compression chamber 412 is heat recovered by the heat exchanger 320b, and condensed water is separated in the first gas-liquid separation unit 230, and then flows into the compression chamber 414. The recovered gas X compressed in the compression chamber 414 is recovered by the heat exchanger 320c and then flows into the first heat exchange unit 310.

  Thus, in this embodiment, the 1st compression part 220, the 2nd compression part 222, and the 3rd compression part 224 are comprised by the one compressor 400, and several separate compressors are comprised. The space (installation space) occupied for the installation of the compressor 400 can be reduced while reducing the introduction cost of the compressor 400 as compared to the installation configuration.

  In addition, impellers 420, 422, and 424 are accommodated in the compression chambers 410, 412, and 414, respectively, and the impellers 420, 422, and 424 are fixed to end portions of different shafts 430, 432, and 434, respectively. The shafts 430, 432, and 434 are rotatably supported by a plurality of bearings 430a, 432a, and 434a, respectively.

  A gear 440 is fixed to the shaft 430, a gear 442 is fixed to the shaft 432, and a gear 444 is fixed to the shaft 434. The compressor 400 is provided with a motor (electric motor) 448. A gear 446 is fixed to an output shaft 450 of the motor 448, and the output shaft 450 is rotatably supported by a plurality of bearings 450a. Yes.

  The gear 446 meshes with the gear 440 and the gear 444, and the power of the motor 448 is transmitted to the gear 440 and the gear 444 via the gear 446. The gear 440 also meshes with the gear 442, and the power of the motor 448 is transmitted to the gear 442 via the gear 446 and the gear 440. Note that the gear 442 may directly mesh with the gear 446 fixed to the output shaft 450 of the motor 448 without using the gear 440.

  As described above, the gears 440, 442, 444, and 446 constitute a speed change mechanism that changes the power of the motor 448 and transmits it to the shafts 430, 432, and 444. That is, the speed change mechanism transmits rotational power having different rotational speeds to each of the plurality of shafts 430, 432, and 434. The shafts 430, 432, and 434 and the impellers 420, 422, and 424 rotate at different rotational speeds by the speed change mechanism. Therefore, the compressor 400 of the present embodiment is constituted by a so-called geared compressor.

  FIG. 3 is an explanatory diagram for explaining the compression container 464 and the connection portion 468 of the compression container 464 and the transmission container 466. The compression container 464, the transmission container 466, and a part of the cross section of the connection portion 468 are illustrated. Extracted and shown.

  As shown in FIG. 3, the compression chamber 414 is a space surrounded by a compression container 464. In other words, the compression container 464 is a housing that forms the outer wall of the compression chamber 414.

  The speed change container 466 is a housing that houses the above-described speed change mechanism, and is connected to the compression container 464 via a connecting portion 468.

  The connecting portion 468 is formed of, for example, a pipe member, and connects a connecting hole 464 a provided in the compression container 464 and a connecting hole 466 a provided in the speed change container 466. The shaft 434 is inserted into the connecting hole 464a, the connecting portion 468, and the connecting hole 466a, and the compression container 464, the connecting portion 468, and the speed change gear are inserted into the compression container 464 and the speed change container 466. It is arranged across the container 466.

  By the way, since the absorbent contained in the lean absorbent L is toxic to the human body, if the lean absorbent L is circulated from the compression container 464 to the speed change container 466, there is a risk of leaking to the work space outside the speed change container 466. Will increase.

  Therefore, a pair of dry gas seals 480a and 480b that prevent the recovery gas from leaking from the compression container 464 to the transmission container 466 are disposed in the coupling portion 468 so as to face each other in the axial direction of the shaft 434. These dry gas seals 480a and 480b are inserted. As a result, the connecting portion 468 is sealed by the dry gas seals 480a and 480b.

  Further, the connecting portion 468 is provided with a through hole 474a penetrating from the outside to the inside, and the nozzle 474b is fitted in a state where the through hole 474a is closed without a gap. The nozzle 474b communicates with the above-described recovery line 254 (see FIG. 1), and in the space 482 surrounded by the connecting portion 468 and the pair of dry gas seals 480a and 480b via the nozzle 474b, the recovery line. 254 communicates.

  At the time of the initial operation of the carbon dioxide recovery device 100, since the recovery gas X does not flow through the recovery line 254, for example, carbon dioxide is supplied from another supply source to the nozzle 474b. Then, after the carbon dioxide recovery device 100 starts operation, when the process is stabilized and the recovery gas X is filled in the recovery line 254, the recovery gas X of the recovery line 254 is compared with the space 482 via the nozzle 474b. Supplied at high pressure. The component of the recovered gas X is almost carbon dioxide as described above.

  By supplying high-pressure carbon dioxide to the space 482 inside the connecting portion 468, purging with carbon dioxide is performed toward the compression chamber 414 sandwiching the dry gas seal 480a. After the recovery line 254 is filled with the recovery gas X, the nozzle 474b is always open and is constantly purged. Further, the nozzle 474b may be opened periodically for an arbitrary time according to an operation instruction from the operator.

  As described above, the compressor 400 of the present embodiment can purge the space 482 without requiring other power after the recovery gas X is filled in the recovery line 254, thereby suppressing energy consumption. Is possible.

  Here, the compression container 464 that forms the outer wall of the compression chamber 414 and the connecting portion 468 that connects the compression container 464 and the transmission container 466 have been described, but the compressor 400 is similar to the compression chamber 414 in the compression chamber 410. 412, a compression container that is a housing forming the outer wall of 412, and a connecting portion that connects the compression container and the speed change container 466. Similar to the connecting portion 468, a pair of dry gas seals are arranged in the connecting portion, and the recovery gas X of the recovery line 254 is supplied to the space surrounded by the connecting portion and the dry gas seal via the nozzle. Is done.

  FIG. 4 is an explanatory diagram for explaining an example of the design calculation of the compressor 400. FIG. 4A shows an example of design calculation of a geared compressor (compressor 400), and FIG. 4B shows an example of design calculation of a single-shaft multi-stage compressor as a comparative example.

  A single-shaft multi-stage compressor does not have a speed change mechanism, and a plurality of impellers are continuously connected to one shaft in the axial direction, and a plurality of compression chambers for accommodating the impellers one by one are connected by piping. . When a single-shaft multi-stage compressor is used in the carbon dioxide separation and recovery unit 110, the recovered gas is compressed to a desired pressure by sequentially flowing from the compression chamber on one end of the shaft to the compression chamber on the other end. Will be.

  However, in the single-shaft multistage compressor, all the impellers are fixed to one shaft, and therefore the rotation speeds of the impellers in the respective compression chambers must be equal. Therefore, when the power of the motor 448 and the number of stages of the compression chamber (impeller) are determined (for example, 1000 kW), the upper limit of the compression ratio of the recovered gas in each compression chamber (hereinafter referred to as the stage pressure ratio) is also determined. Therefore, in order to compress the recovered gas to a desired pressure, for example, 1300 kPa (A) as described above, the number of stages of the compression chamber (impeller) must be increased. In the example of the design calculation shown in FIG. 4B, the number of stages increases to nine.

  On the other hand, since the compressor 400 which is a geared compressor has the speed change mechanism as described above, the rotational speeds of the impellers 420, 422 and 424 are variable depending on the gear ratio.

  In the design calculation example shown in FIG. 4A, the impeller 420 of the first stage (stage 1 in FIG. 4A) has a gear ratio so that the impeller peripheral speed determined by the rotational speed and the impeller diameter is relatively large. In the compression chamber 410, the recovered gas is compressed at a relatively high stage pressure ratio.

  The impeller 422 in the second stage (stage 2 in FIG. 4A) and the impeller 424 in the third stage (stage 3 in FIG. 4A) are designed so that the rotational speed increases as the rear stage. By increasing the number of revolutions, while maintaining a sufficient flow rate even if the impeller diameter is reduced, reducing the impeller diameter reduces the stage pressure ratio, but the compressive force that further compresses the high-pressure recovered gas. Secure.

  As described above, the compressor 400 according to the present embodiment can vary the rotation speeds of the impellers 420, 422, and 424 depending on the speed change mechanism. The degree of freedom is high, and the number of stages can be reduced compared to a single-shaft multi-stage compressor. By reducing the number of stages, the compressor 400 can further reduce the introduction cost and the installation space.

  In addition, since the single-shaft multi-stage compressor has a plurality of impellers arranged in the axial direction, if the interval between the stages (impellers) is narrowed, an installation space for a heat exchanger or the like disposed between the stages. It is difficult to ensure sufficient, and if the interval between each stage (impeller) is widened, the larger the number of stages, the larger the size in the axial direction.

  However, in the compressor 400 of this embodiment, as shown in FIG. 2, a plurality of shafts 430, 432, 434 are arranged in parallel to the axial direction. Therefore, the gears 440, 442, and 444 may be engaged with the gear 446 fixed to the output shaft 450 of the motor 448 directly or indirectly through another gear, and the impellers 420, 422, and 424 may be engaged with each other. Since the degree of freedom of arrangement is high, the installation space can be easily reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  Moreover, in embodiment mentioned above, although the case where the fillers 122 and 144 were comprised with ferrous metal materials, such as stainless steel and carbon steel, was mentioned as an example, the process of lean absorption liquid L or rich absorption liquid R was demonstrated. A material having durability and corrosion resistance at temperature and having a shape capable of providing a desired contact area may be appropriately selected.

  In the above-described embodiment, the case where the compressor 400 includes the three compression chambers 410, 412, and 414 and the impellers 420, 422, and 424 has been described. However, the number of the compression chambers and the impellers may be two or four. There may be more than one.

  In the above-described embodiment, the case where each impeller 420, 422, 424 is fixed to different shafts 430, 432, 434 has been described. However, the number of rotations is two or more shafts to which the impeller is fixed. If they are different, one impeller may be fixed to both ends of one shaft.

  INDUSTRIAL APPLICABILITY The present invention can be used for a carbon dioxide recovery device that separates and recovers carbon dioxide from a mixed gas containing carbon dioxide such as exhaust gas accompanying combustion.

DESCRIPTION OF SYMBOLS 100 ... Carbon dioxide recovery device 120 ... Absorption part 140 ... Regeneration part 210 ... Passage line 250 ... 2nd gas-liquid separation part (gas-liquid separation part)
320 ... 2nd heat exchange part (heat exchange part)
400 ... compressors 410, 412, 414 ... compression chambers 320a, 320b, 320c ... heat exchanger (heat exchange section)
420, 422, 424 ... impellers 440, 442, 444, 446 ... gears (transmission mechanism)
464 ... Compression container 466 ... Transmission container 468 ... Connection part 480a, 480b ... Dry gas seal 482 ... Space

Claims (2)

An absorption part for bringing a gas containing carbon dioxide into contact with an absorption liquid, causing the absorption liquid to absorb carbon dioxide, and generating a carbon dioxide-containing absorption liquid;
A heating unit that heats the carbon dioxide-containing absorption liquid and releases carbon dioxide from the carbon dioxide-containing absorption liquid, thereby regenerating the carbon dioxide-containing absorption liquid into the absorption liquid;
A passing line through which the recovered gas containing carbon dioxide and water vapor discharged from the regeneration section passes;
A compressor provided in the passage line for compressing the recovered gas;
A heat exchanging unit that recovers heat generated by the compression of the recovered gas in the compressor and supplies the heat to the regeneration unit;
With
The compressor is
Multiple shafts;
A plurality of impellers fixed to either end of the shaft;
A plurality of compression chambers in which any one of the plurality of impellers is accommodated and the recovered gas is compressed by rotation of the impeller;
A transmission mechanism for transmitting rotational power having different rotational speeds to each of the plurality of shafts;
Have
A centrifugal compressor in which the recovered gas is circulated through the plurality of compression chambers in order to increase the compression rate of the recovered gas,
The carbon dioxide recovery device, wherein the heat exchanging unit is disposed in a subsequent stage of each of the plurality of compression chambers. A gas-liquid separation unit that is provided in the passage line and separates water condensed from the recovered gas by collecting heat by the heat exchange unit;
A recovery line through which the recovered gas from which water has been separated by the gas-liquid separator passes;
Further comprising
The compressor is
A plurality of compression containers forming outer walls of the plurality of compression chambers;
A speed change container connected to the plurality of compression containers and containing the speed change mechanism;
Connecting each of the plurality of compression containers and the speed change container, and a plurality of connection parts through which the shafts accommodated in the compression container and the speed change container are inserted;
A pair of dry gas seals inserted through the shaft and disposed opposite to each other in the axial direction of the shaft inside the connecting portion to prevent leakage of the recovered gas from the compression container to the transmission container;
Further comprising
The carbon dioxide recovery device according to claim 1, wherein the recovery line communicates with a space surrounded by the connecting portion and the pair of dry gas seals.

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